This could be a good or bad thing, depending on your point of view. On the one hand, you can now creep on people—perhaps a colleague or a former flame you spot on the service—without them finding out. On the other hand, however, if you spot a hottie you're interested in, you'll no longer be able to get their attention by simply visiting their profile a couple times, meaning you might be forced to make the first move.
OKCupid has not formally announced this change on its blog, but has started to notify users about it via email, according to a post on Reddit.